Poor little Scott Schwartz is a notorious case. There's also Sylvester Stallone (cheapie flick a short time before Rocky) Traci Lords (she was on Married With Children, if you count that as acting) and of course Madonna.

I hope someone tries to find the hilarious story Sonnenfeld told about his first job shooting porn. He was shooting an anal scene in close up and the actor pulled out, leaving Sonnenfeld with a face full of excrement...

From "Sgt. Peckers Lonely Hearts Club Gang Bang" to "Rules of Attraction"! Cool!

Then there are a couple of porn stars or ex-porn stars that have appeared in Europen (more specifically French) arthouse films. Rocco Siffredi ( http://us.imdb.com/name/nm0797382/ ) was actually very good acting-wise in Catherine Breillant's ROMANCE and some of the women in Virginie Despentes god-awful (IMO) BAISE MOI are ex-porn actresses.

Kobe Tai had a small part as a hooker in Very Bad Things.

Ashlyn Gere played in an episode of the X-Files, and had a recurring role in Space: Above and Beyond. She was also in the Willard remake under the name Kim McKamy.